1. For the stock, place the chicken, ginger, and green onion in a pot. Pour over water so it covers the chicken by about one inch.
Add needed salt to season the chicken. Simmer over medium-low heat, making sure to skim and discard the foam, until chicken is cooked through. Set chicken aside to cool and discard aromatics.
2. Bring broth to boil, then add cauliflower, cooking until fork-tender. Add corn and heat until warmed through.
3. Shred cooked chicken and combine with slaw ingredients. You may soak the onions in water beforehand to remove its strong bite.
4. Reserve a quarter cup of corn, then blend the rest with the cauliflower and broth. Back in the pot, season to taste with fish sauce
and pepper.
5. To serve, ladle hot soup into bowls and top with slaw.
Optional: For a crispy topping, slice reserved chicken skin into small pieces, and fry over medium high heat until the fat has rendered and they are crisp.